Confusion about cells in parallel

Question

I cant understand why cells in parallel will last longer. Could someone please explain?

Answer 1

Here's one way to think about it.

Consider the case that one cell is connected across a resistor. Stipulate that the cell has a capacity of 1 amp-hour and that the cell delivers 1 amp of current to the resistor when first connected.

You should expect that the cell will discharge in roughly 1 hour.

Now, disconnect the discharged cell, and connect to the resistor two cells in parallel, identical to the cell used before, and observe that, as before, 1 amp of current is delivered to the resistor.

Since the cells are identical, it follows that the current through each cell is the same and so, there is 1/2 amp through each cell.

Since each cell has a capacity of 1 amp-hour, and since each cell is (nominally) delivering 1/2 amp of current, it follows that each cell will discharge in roughly 2 hours which is twice as long as one cell alone.

Answer 2

Two cells in parallel driving the same load are sharing it, each furnishes half the power required to drive it and so two cells will last twice as long as one cell driving the same load.

Answer 3

A battery is like a store in which you shop for electrons. If two are in parallel you have more stuff you can buy simultaneously; that is you can have two guys shopping at the same time, then get on the road and go home. If they are connected in series first you have to visit one store and then you may go to the next after which you can go home, only you do the shopping, so it takes longer to empty it.